Issues printing with filaments with particulates  

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rwetmore
(@rwetmore)
New Member

I've been having a blast printing with my new Mini. It has been nearly flawless. Well, aside from a few niggling firmware issues like having to constantly reset the printer after prints.

Flawless—except when I try to print filaments with fibers or sparkles. The print head clogs, the printer underextrudes, it's impossible to unload filament, etc.

When I couldn't unload filament once, I unscrewed the cap on the hotend-side of the PTFE tube to cut the filament to make it easier to pull out. When I went to reinsert the tube, it didn't seem to go far enough into the hotend. The compression fitting is fused to the tube and I can't seem to move it. I hoped I might be able to adjust the fit by moving the fitting down a bit. Should I be able to do this? I don't want to risk ruining anything by forcing the issue unless I know it'll work.

With standard filaments, I don't have any issues. Any suggestions?

Posted : 17/02/2020 8:31 pm
RedDawg
(@reddawg)
Trusted Member

I'll have more to say in a different post (that's more of an over-all review), but I'm having issues with ALL filaments, especially if they happen to be ANY larger than the nominal 1.75mm, even by a tiny amount. I think the bowden tube has been speced too small. It's fine for applications like the MMU, but add a compression fixture and it does EXACTLY what it was designed to do, compress the tube, PERMANENTLY! I'm finding that a #47 drill bit (actually measuring 1.98mm) is a good snug fit inside the two short tubes (one in the hot end, the other in the extruder), however it WILL NOT FIT into the longer section between the hot end and the extruder (with the compression fittings.) You have to go to a #49 bit (1.84mm) before it will enter  this tube, and even then it stops where the compression ring has reduced the diameter even further. To get past this point, you have to go to a #50 bit (1.77mm), so this tube is very intolerant to over-sized filaments. Even ones that are exactly 1.75mm exhibit very high friction within this tube. I'm having some success using the #47 bit to open up each end of the longer tube to beyond the inboard edge of the compression ring, although I expect JP would not recommend that. Just make sure you blow out any/all shavings the bit may leave behind. When reassembling the tube, first hand-tighten only, then add a minimal amount of torque with the wrench. If you over-tighten it, the ring will compress the tube further and you will be back where you started. You will probably damage the tube if you try to move the ring(s) that have embedded themselves into the plastic. Better to order new tubes (without fittings), move the rings over and DO NOT tighten the threaded portion more than the amount needed to keep the tube from "walking" out. More to come.

1. "Every creative act results from a sudden cessation of stupidity." -Edwin Land, inventor of the Polaroid Land Camera. 2. "The experiment can always be solved with the materials in the room." -My college physics professor. 3. "If…...
Posted : 17/02/2020 9:44 pm
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